Optical unit, illumination optical apparatus, exposure apparatus, and device manufacturing method

ABSTRACT

An illumination optical apparatus has an optical unit. The optical unit has a light splitter to split an incident beam into two beams; a first spatial light modulator which can be arranged in an optical path of a first beam; a second spatial light modulator which can be arranged in an optical path of a second beam; and a light combiner which combines a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator; each of the first spatial light modulator and the second spatial light modulator has a plurality of optical elements arranged two-dimensionally and controlled individually.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. application Ser. No. 14/664,022 filedMar. 20, 2015, which is a Continuation of U.S. application Ser. No.13/449,115 filed Apr. 17, 2012, which is a Division of U.S. applicationSer. No. 12/245,021 filed Oct. 3, 2008 (now U.S. Pat. No. 8,379,187),which is based upon and claims the benefit of priorities from U.S.Provisional Application No. 61/006,446, filed on Jan. 14, 2008 and U.S.Provisional Application No. 60/960,996, filed on Oct. 24, 2007, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field

An embodiment of the present invention relates to an optical unit, anillumination optical apparatus, an exposure apparatus, and a devicemanufacturing method.

2. Description of the Related Art

In a typical exposure apparatus of this type, a light beam emitted froma light source travels through a fly's eye lens as an optical integratorto form a secondary light source (a predetermined light intensitydistribution on an illumination pupil in general) as a substantialsurface illuminant consisting of a large number of light sources. Thelight intensity distribution on the illumination pupil will be referredto hereinafter as “illumination pupil luminance distribution.” Theillumination pupil is defined as a position such that an illuminationtarget surface becomes a Fourier transform surface of the illuminationpupil by action of an optical system between the illumination pupil andthe illumination target surface (a mask or a wafer in the case of theexposure apparatus).

Beams from the secondary light source are condensed by a condenser lensto supposedly illuminate the mask on which a predetermined pattern isformed. Light passing through the mask travels through a projectionoptical system to be focused on the wafer, whereby the mask pattern isprojected (or transferred) onto the wafer to effect exposure thereof.Since the pattern formed on the mask is a highly integrated one, an evenilluminance distribution must be obtained on the wafer in order toaccurately transfer this fine pattern onto the wafer.

There is a conventionally proposed illumination optical apparatuscapable of continuously changing the illumination pupil luminancedistribution (and, therefore, the illumination condition) without use ofa zoom optical system (cf. Japanese Patent Application Laid-open No.2002-353105). The illumination optical apparatus disclosed in theApplication Laid-open No. 2002-353105 uses a movable multi-mirrorcomposed of a large number of micro mirror elements which are arrangedin an array form and angles and directions of inclination of which areindividually drive-controlled, and is so configured that an incidentbeam is divided into beams of small units corresponding to reflectingsurfaces of the mirror elements, the beams of small units are folded bythe multi-mirror to convert a cross section of the incident beam into adesired shape or a desired size, and, in turn, a desired illuminationpupil luminance distribution is realized.

SUMMARY

An embodiment of the present invention provides an illumination opticalapparatus capable of realizing illumination conditions of greatervariety in terms of the shape and size of the illumination pupilluminance distribution. An embodiment of the present invention providesan exposure apparatus capable of performing good exposure under anappropriate illumination condition realized according to a patterncharacteristic, using the illumination optical apparatus capable ofrealizing the illumination conditions of great variety.

For purposes of summarizing the invention, certain aspects, advantages,and novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any particular embodiment of the invention. Thus, theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessary achieving other advantages as may be taught or suggestedherein.

A first embodiment of the present invention provides an optical unitcomprising:

a light splitter to split an incident beam traveling in an incidentlight path, into a plurality of beams;

a first spatial light modulator which can be arranged ill an opticalpath of a first beam out of the plurality of beams;

a second spatial light modulator which can be arranged in an opticalpath of a second beam out of the plurality of beams; and

a light combiner to combine a beam having passed via the first spatiallight modulator, with a beam having passed via the second spatial lightmodulator, and to direct a resultant beam to an exiting light path;

wherein at least one spatial light modulator out of the first spatiallight modulator and the second spatial light modulator has a pluralityof optical elements arranged two-dimensionally and controlledindividually; and

wherein the incident light path on the light splitter side and theexiting light path on the light combiner side extend in the samedirection.

A second embodiment of the present invention provides an illuminationoptical apparatus to illuminate an illumination target surface on thebasis of light from a light source, the illumination optical apparatuscomprising:

the optical unit of the first aspect; and

a distribution forming optical system which forms a predetermined lightintensity distribution on an illumination pupil of the illuminationoptical apparatus, based on the beams having passed via the first andsecond spatial light modulators.

A third embodiment of the present invention provides an exposureapparatus comprising the illumination optical apparatus of the secondaspect for illuminating a predetermined pattern, the exposure apparatusperforming exposure of the predetermined pattern on a photosensitivesubstrate.

A fourth embodiment of the present invention provides a devicemanufacturing method comprising:

effecting the exposure of the predetermined pattern on thephotosensitive substrate, using the exposure apparatus of the thirdaspect;

developing the photosensitive substrate onto which the pattern has beentransferred, to form a mask layer in a shape corresponding to thepattern on a surface of the photosensitive substrate; and

processing the surface of the photosensitive substrate through the masklayer.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is a drawing schematically showing a configuration of an exposureapparatus according to an embodiment of the present invention.

FIG. 2 is a drawing schematically showing a configuration of a spatiallight modulation unit.

FIG. 3 is a perspective view schematically showing a configuration of acylindrical micro fly's eye lens.

FIG. 4 is a drawing schematically showing a light intensity distributionof a quadrupolar shape formed on a pupil plane of an afocal lens in theembodiment.

FIG. 5 is a drawing schematically showing an example of forming anillumination pupil luminance distribution of a pentapolar shape in theembodiment.

FIG. 6 is a drawing schematically showing a configuration of a spatiallight modulation unit according to a modification example in which alight splitter and a light combiner include a common polarization beamsplitter.

FIG. 7 is a drawing schematically showing a configuration of a spatiallight modulation unit according to another modification example havingtransmissive spatial light modulators.

FIG. 8 is a drawing schematically showing a configuration of an exposureapparatus according to a modification example having a polarizationcontrol unit.

FIG. 9 is a drawing schematically showing a major configuration of amodification example using a diffractive optical element as a lightsplitter.

FIG. 10 is a drawing schematically showing a configuration of thespatial light modulation unit shown in FIG. 9.

FIG. 11 a partial perspective view of a spatial light modulator in thespatial light modulation unit shown in FIG. 9.

FIG. 12 is a drawing schematically showing a major configuration of amodification example using a prism unit as a light splitter.

FIG. 13 is a flowchart showing manufacturing blocks of semiconductordevices.

FIG. 14 is a flowchart showing manufacturing blocks of a liquid crystaldevice such as a liquid-crystal display device.

DESCRIPTION

Embodiments of the present invention will be described on the basis ofthe accompanying drawings. FIG. 1 is a drawing schematically showing aconfiguration of an exposure apparatus according to an embodiment of thepresent invention. FIG. 2 is a drawing schematically showing aconfiguration of a spatial light modulation unit. In FIG. 1, the Z-axisis set along a direction of a normal to a wafer W being a photosensitivesubstrate, the Y-axis along a direction parallel to the plane of FIG. 1in a surface of the wafer W, and the X-axis along a directionperpendicular to the plane of FIG. 1 in the surface of the wafer W.

With reference to FIG. 1, the exposure apparatus of the presentembodiment is provided with a light source 1 for supplying exposurelight (illumination light). The light source 1 can be, for example, anArF excimer laser light source which supplies light at the wavelength of193 nm, or a KrF excimer laser light source which supplies light at thewavelength of 248 nm. Light emitted from the light source 1 is expandedinto a beam of a required sectional shape by a shaping optical system 2and then the expanded beam is incident to a spatial light modulationunit 3.

The spatial light modulation unit 3, as shown in FIG. 2, has a pair ofprism members 31 and 32, and a pair of spatial light modulators 33 and34. The light incident along the optical axis AX into an entrance face31 a of the prism member 31 in the spatial light modulation unit 3propagates inside the prism member 31 and thereafter impinges upon apolarization separating film 35 formed between the prism members 31 and32. S-polarized light reflected by the polarization separating filmpropagates inside the prism member 31 and thereafter impinges upon thefirst spatial light modulator 33.

The first spatial light modulator 33 has a plurality of mirror elements(optical elements in general) 33 a arranged two-dimensionally, and adrive unit 33 b (not shown in FIG. 1) which individually controls anddrives postures of the mirror elements 33 a. Similarly, the secondspatial light modulator 34 has a plurality of mirror elements 34 aarranged two-dimensionally, and a drive unit 34 b (not shown in FIG. 1)which individually controls and drives postures of the mirror elements34 a. The drive units 33 b, 34 b individually control and drive thepostures of the mirror elements 33 a, 34 a in accordance with commandsfrom an unrepresented control unit.

Light reflected by the mirror elements 33 a of the first spatial lightmodulator 33 propagates inside the prism member 31 and thereafter isincident in the s-polarized state to a polarization separating film 36formed between the prism members 31 and 32. The light having traveledvia the first spatial light modulator 33 to be reflected on thepolarization separating film 36, propagates inside the prism member 31and is then emitted from an exit face 31 b of the prism member 31 to theoutside of the spatial light modulation unit 3. In a standard state inwhich reflecting surfaces of all the mirror elements 33 a in the firstspatial light modulator 33 are positioned along the XY plane, the lighthaving traveled along the optical axis AX into the spatial lightmodulation unit 3 and then via the first spatial light modulator 33 isemitted along the optical axis AX from the spatial light modulation unit3.

On the other hand, p-polarized light having passed through thepolarization separating film 35 propagates inside the prism member 32and is totally reflected on an interface 32 a between the prism member32 and a gas (air or inert gas) 37. Thereafter, the totally reflectedlight is incident to the second spatial light modulator 34. Lightreflected by the mirror elements 34 a in the second spatial lightmodulator 34 propagates inside the prism member 32 and is totallyreflected on an interface 32 b between the prism member 32 and the gas37. Thereafter, the totally reflected light is incident in thep-polarized state to the polarization separating film 36 formed betweenthe prism members 31 and 32.

The light having traveled via the second spatial light modulator 34 andhaving been transmitted by the polarization separating film 36,propagates inside the prism member 31 and then is emitted from the exitface 31 b of the prism member 31 to the outside of the spatial lightmodulation unit 3. In a standard state in which reflecting surfaces ofall the mirror elements 34 a in the second spatial light modulator 34are positioned along the XY plane, the light having traveled along theoptical axis AX into the spatial light modulation unit 3 and then viathe second spatial light modulator 34, is emitted along the optical axisAX from the spatial light modulation unit 3.

In the spatial light modulation unit 3, as described above, thepolarization separating film 35 formed between the prism members 31 and32 constitutes a light splitter to split the incident beam into twobeams (a plurality of beams in general). The polarization separatingfilm 36 formed between the prism members 31 and 32 constitutes a lightcombiner to combine the beam having traveled via the first spatial lightmodulator 33, with the beam having traveled via the second spatial lightmodulator 34.

The light emitted from the spatial light modulation unit 3 is thenincident to an afocal lens 4. The afocal lens 4 is an afocal system(afocal optic) that is so set that the front focal point thereof isapproximately coincident with the position of the mirror elements 33 aof the first spatial light modulator 33 and with the position of themirror elements 34 a of the second spatial light modulator 34 and thatthe rear focal point thereof is approximately coincident with a positionof a predetermined plane 5 indicated by a dashed line in the drawing.

Therefore, the s-polarized beam having traveled via the first spatiallight modulator 33 forms, for example, a light intensity distribution ofa Z-directionally dipolar shape consisting of two circular lightintensity distributional areas spaced in the Z-direction with a centeron the optical axis AX, on the pupil plane of the afocal lens 4, andthereafter is emitted in the dipolar angle distribution from the afocallens 4. On the other hand, the p-polarized beam having traveled via thesecond spatial light modulator 34 forms, for example, a light intensitydistribution of an X-directionally dipolar shape consisting of twocircular light intensity distributional areas spaced in the X-directionwith a center on the optical axis AX, on the pupil plane of the afocallens 4, and thereafter is emitted in the dipolar angle distribution fromthe afocal lens 4.

A conical axicon system 6 is arranged at the position of the pupil planeof the afocal lens 4 or at a position near it in the optical pathbetween a front lens unit 4 a and a rear lens unit 4 b of the afocallens 4. The configuration and action of the conical axicon system 6 willbe described later. The beam having passed through the afocal lens 4travels through a zoom lens 7 for variation in a value (σvalue=mask-side numerical aperture of the illumination opticalapparatus/mask-side numerical aperture of the projection optical system)and then enters a cylindrical micro fly's eye lens 8.

The cylindrical micro fly's eye lens 8, as shown in FIG. 3, is composedof a first fly's eye member 8 a arranged on the light source side and asecond fly's eye member 8 b arranged on the mask side. Cylindrical lensgroups 8 aa and 8 ba arrayed in the X-direction are formed each at thepitch p1 in the light-source-side surface of the first fly's eye member8 a and in the light-source-side surface of the second fly's eye member8 b, respectively. Cylindrical lens groups 8 ab and 8 bb arrayed in theZ-direction are formed each at the pitch p2 (P2>p1) in the mask-sidesurface of the first fly's eye member 8 a and in the mask-side surfaceof the second fly's eye member 8 b, respectively.

When attention is focused on the refracting action in the X-direction ofthe cylindrical micro fly's eye lens 8 (i.e., the refracting action inthe XY plane), the wavefront of a parallel beam incident along theoptical axis AX is divided at the pitch pi along the X-direction by thecylindrical lens group 8 aa formed on the light source side of the firstfly's eye member 8 a, the divided beams are condensed by refractingfaces of the cylindrical lens group, the condensed beams are thencondensed by refracting faces of the corresponding cylindrical lenses inthe cylindrical lens group 8 ba formed on the light source side of thesecond fly's eye member 8 b, and the condensed beams are converged onthe rear focal plane of the cylindrical micro fly's eye lens 8.

When attention is focused on the refracting action in the Z-direction ofthe cylindrical micro fly's eye lens 8 (i.e., the refracting action inthe YZ plane), the wavefront of a parallel beam incident along theoptical axis AX is divided at the pitch p2 along the Z-direction by thecylindrical lens group 8 ab formed on the mask side of the first fly'seye member 8 a, the divided beams are condensed by refracting faces ofthe cylindrical lens group, the condensed beams are then condensed byrefracting faces of the corresponding cylindrical lenses in thecylindrical lens group 8 bb formed on the mask side of the second fly'seye member 8 b, and the condensed beams are converged on the rear focalplane of the cylindrical micro fly's eye lens 8.

As described above, the cylindrical micro fly's eye lens 8 is composedof the first fly's eye member 8 a and the second fly's eye member 8 b ineach of which the cylindrical lens groups are arranged on the two sidefaces thereof, and exercises the same optical function as a micro fly'seye lens in which a large number of micro refracting faces of arectangular shape in the size of p1 in the X-direction and in the sizeof p2 in the Z-direction are integrally formed horizontally andvertically and densely. The cylindrical micro fly's eye lens 8 is ableto achieve smaller change in distortion due to variation in surfaceshapes of the micro refracting faces and, for example, to keep lessinfluence on the illuminance distribution from manufacture errors of thelarge number of micro refracting faces integrally formed by etching.

The position of the predetermined plane 5 is located near the frontfocal point of the zoom lens 7 and the entrance surface of thecylindrical micro fly's eye lens 8 is located near the rear focal pointof the zoom lens 7. In other words, the zoom lens 7 sets thepredetermined plane 5 and the entrance surface of the cylindrical microfly's eye lens 8 substantially in the Fourier transform relation and,thus, keeps the pupil plane of the afocal lens 4 approximately opticallyconjugate with the entrance surface of the cylindrical micro fly's eyelens 8.

Therefore, for example, a quadrupolar illumination field consisting oftwo circular light intensity distributional areas spaced in theZ-direction with a center on the optical axis AX and two circular lightintensity distributional areas spaced in the X-direction with a centeron the optical axis AX is formed on the entrance surface of thecylindrical micro fly's eye lens 8 as on the pupil plane of the afocallens 4. The overall shape of this quadrupolar illumination fieldsimilarly varies depending upon the focal length of the zoom lens 7. Therectangular micro refracting faces as wavefront division units in thecylindrical micro fly's eye lens 8 are of a rectangular shape similar toa shape of an illumination field to be formed on the mask M (and,therefore, similar to a shape of an exposure region to be formed on thewafer W).

The beam incident to the cylindrical micro fly's eye lens 8 istwo-dimensionally divided to form a secondary light source with a lightintensity distribution approximately identical with the illuminationfield formed by the incident beam, i.e., a secondary light source of aquadrupolar shape (quadrupolar illumination pupil luminancedistribution) consisting of two circular substantial surface illuminantsspaced in the Z-direction with a center on the optical axis AX and twocircular substantial surface illuminants spaced in the X-direction witha center on the optical axis AX, on or near its rear focal plane (andthus on the illumination pupil). Beams from the secondary light sourceformed on or near the rear focal plane of the cylindrical micro fly'seye lens 8 are then incident to an aperture stop 9 located near it.

The aperture stop 9 has quadrupolar apertures (light transmittingportions) corresponding to the secondary light source of the quadrupolarshape formed on or near the rear focal plane of the cylindrical microfly's eye lens 8. The aperture stop 9 is configured so as to bedetachable with respect to the illumination optical path and to beswitchable with a plurality of aperture stops having apertures ofdifferent sizes and shapes. A method of switching the aperture stops canbe, for example, a known turret method or slide method. The aperturestop 9 is arranged at a position approximately optically conjugate withan entrance pupil plane of projection optical system PL described later,and defines a range of the secondary light source that contributes toillumination.

The beams from the secondary light source limited by the aperture stop 9travel through a condenser optical system 10 to supposedly illuminate amask blind 11. In this way, an illumination field of a rectangular shapeaccording to the shape and focal length of the rectangular microrefracting faces as wavefront division units of the cylindrical microfly's eye lens 8 is formed on the mask blind 11 as an illumination fieldstop. Beams having passed through a rectangular aperture (lighttransmitting portion) of the mask blind 11 is condensed by an imagingoptical system 12 to superposedly illuminate a mask M on which apredetermined pattern is formed. Namely, the imaging optical system 12forms an image of the rectangular aperture of the mask blind 11 on themask M.

A beam having passed through the mask M held on a mask stage MS travelsthrough the projection optical system PL to form an image of the maskpattern on a wafer (photosensitive substrate) W held on a wafer stageWS. In this manner, the pattern of the mask M is sequentiallytransferred into each of exposure regions on the wafer W by performingone-shot exposure or scan exposure while two-dimensionally driving andcontrolling the wafer stage WS in the plane (XV plane) perpendicular tothe optical axis AX of the projection optical system PL and, therefore,while two-dimensionally driving and controlling the wafer W.

The conical axicon system 6 is composed of the following membersarranged in the order named from the light source side: first prismmember 6 a with a plane on the light source side and with a refractingsurface of a concave conical shape on the mask side; and second prismmember 6 b with a plane on the mask side and with a refracting surfaceof a convex conical shape on the light source side. The concave conicalrefracting surface of the first prism member 6 a and the convex conicalrefracting surface of the second prism member 6 b are complementarilyformed so as to be able to contact each other. At least one member outof the first prism member 6 a and the second prism member 6 b isconfigured to be movable along the optical axis AX, whereby the spacingis made variable between the concave conical refracting surface of thefirst prism member 6 a and the convex conical refracting surface of thesecond prism member 6 b. For easier understanding, the action of theconical axicon system 6 and the action of the zoom lens 7 will bedescribed with focus on the secondary light source of the quadrupolar orannular shape.

In a state in which the concave conical refracting surface of the firstprism member 6 a and the convex conical refracting surface of the secondprism member 6 b contact each other, the conical axicon system 6functions as a plane-parallel plate and causes no effect on thesecondary light source of the quadrupolar or annular shape formed.However, as the concave conical refracting surface of the first prismmember 6 a and the convex conical refracting surface of the second prismmember 6 b are separated away from each other, the outside diameter(inside diameter) of the quadrupolar or annular secondary light sourcevaries while keeping constant the width of the quadrupolar or annularsecondary light source (half of a difference between a diameter (outsidediameter) of a circle circumscribed to the quadrupolar secondary lightsource and a diameter (inside diameter) of a circle inscribed therein;half of a difference between the outside diameter and the insidediameter of the annular secondary light source). Namely, the annularratio (inside diameter/outside diameter) and the size (outside diameter)of the quadrupolar or annular secondary light source vary.

The zoom lens 7 has a function to enlarge or reduce the overall shape ofthe quadrupolar or annular secondary light source similarly (orisotropically). For example, as the focal length of the zoom lens 7 isincreased from a minimum value to a predetermined value, the overallshape of the quadrupolar or annular secondary light source is similarlyenlarged. In other words, the width and size (outside diameter) of thesecondary light source both vary, without change in the annular ratio ofthe quadrupolar or annular secondary light source, by the action of thezoom lens 7. In this manner, the annular ratio and size (outsidediameter) of the quadrupolar or annular secondary light source can becontrolled by the actions of the conical axicon system 6 and the zoomlens 7.

In the present embodiment, the spatial light modulators 33, 34 to beused can be, for example, those continuously changing each oforientations of the mirror elements 33 a, 34 a arrangedtwo-dimensionally. Such spatial light modulators can be selected, forexample, from the spatial light modulators disclosed in Japanese PatentApplication Laid-open (Translation of PCT Application) No. 10-503300 andEuropean Patent Application Publication EP 779530 corresponding thereto,Japanese Patent Application Laid-open No. 2004-78136 and U.S. Pat. No.6,900,915 corresponding thereto, Japanese Patent Application Laid-open(Translation of PCT Application) No. 2006-524349 and U.S. Pat. No.7,095,546 corresponding thereto, and Japanese Patent ApplicationLaid-open No. 2006-113437. It is also possible to control theorientations of the mirror elements 33 a, 34 a arrangedtwo-dimensionally, in a plurality of discrete steps. The teachings inEuropean Patent Application Publication EP 779530, U.S. Pat. No.6,900,915, and U.S. Pat. No. 7,095,546 are incorporated herein byreference.

In the first spatial light modulator 33, each of the postures of themirror elements 33 a varies by the action of the drive unit 33 boperating according to a control signal from the control unit, wherebyeach mirror element 33 a is set in a predetermined orientation. Thes-polarized light reflected at respective predetermined angles by themirror elements 33 a of the first spatial light modulator 33 forms, forexample, two circular light intensity distributional areas 41 a and 41 bspaced in the Z-direction with a center on the optical axis AX, on thepupil plane of the afocal lens 4, as shown in FIG. 4. The light formingthe light intensity distributional areas 41 a and 41 b has thepolarization direction along the X-direction as indicated bydouble-headed arrows in the drawing.

Similarly, in the second spatial light modulator 34, each of thepostures of the mirror elements 34 a varies by the action of the driveunit 34 b operating according to a control signal from the control unit,whereby each mirror element 34 a is set in a predetermined orientation.The p-polarized light reflected at respective predetermined angles bythe mirror elements 34 a of the second spatial light modulator 34 forms,for example, two circular light intensity distributional areas 41 c and41 d spaced in the X-direction with a center on the optical axis AX, onthe pupil plane of the afocal lens 4, as shown in FIG. 4. The lightforming the light intensity distributional areas 41 c and 41 d has thepolarization direction along the Z-direction as indicated bydouble-headed arrows in the drawing. When the polarization state of thebeam incident into the spatial light modulation unit 3 is circularpolarization or linear polarization with the polarization direction atan angle of 45° to the X-axis and Z-axis (which will be referred tohereinafter as “45° linear polarization”), the light intensities of thefour light intensity distributional areas 41 a-41 d become equal to eachother.

The light forming the quadrupolar light intensity distribution 41 on thepupil plane of the afocal lens 4 forms the light intensity distributionof the quadrupolar shape corresponding to the light intensitydistributional areas 41 a-41 d on the entrance surface of thecylindrical micro fly's eye lens 8, and on the rear focal plane of thecylindrical micro fly's eye lens 8 or on the illumination pupil near it(the position where the aperture stop 9 is arranged). Namely, the afocallens 4, zoom lens 7, and cylindrical micro fly's eye lens 8 constitute adistribution forming optical system which forms a predetermined lightintensity distribution on the illumination pupil of the illuminationoptical apparatus (2-12), based on the beams having traveled via thefirst spatial light modulator 33 and the second spatial light modulator34. Furthermore, the light intensity distribution of the quadrupolarshape corresponding to the light intensity distributional areas 41 a-41d is also formed at other illumination pupil positions opticallyconjugate with the aperture stop 9, i.e., at the pupil position of theimaging optical system 12 and at the pupil position of the projectionoptical system PL.

The exposure apparatus performs exposure under an appropriateillumination condition according to a pattern characteristic, in orderto highly accurately and faithfully transfer the pattern of the mask Monto the wafer W. In the present embodiment, the illumination pupilluminance distribution to be formed is the quadrupolar illuminationpupil luminance distribution corresponding to the quadrupolar lightintensity distribution 41 shown in FIG. 4 and the beams passing throughthis quadrupolar illumination pupil luminance distribution are set in acircumferential polarization state. In the circumferential polarizationquadrupolar illumination based on the quadrupolar illumination pupilluminance distribution in the circumferential polarization state, thelight impinging upon the wafer W as a final illumination target surfaceis in a polarization state in which the principal component iss-polarized light.

Here the s-polarized light is linearly polarized light with thepolarization direction along a direction normal to a plane of incidence(which is polarized light with the electric vector vibrating in thedirection normal to the plane of incidence). The plane of incidence isdefined as a plane that includes a point where light impinges upon aboundary surface of a medium (illumination target surface: surface ofwafer W) and that includes a normal to the boundary surface at thatpoint and a direction of incidence of the light. As a consequence, thecircumferential polarization quadrupolar illumination achieves animprovement in optical performance of the projection optical system (thedepth of focus and others), whereby a good mask pattern image isobtained with high contrast on the wafer (photosensitive substrate).

Since the present embodiment uses the spatial light modulation unit 3with the pair of spatial light modulators 33, 34 in which the posturesof the mirror elements 33 a, 34 a each are individually changed, it isfeasible to freely and quickly change the illumination pupil luminancedistribution consisting of the first light intensity distribution in thes-polarized state formed on the illumination pupil by the action of thefirst spatial light modulator 33 and the second light intensitydistribution in the p-polarized state formed on the illumination pupilby the action of the second spatial light modulator 34. In other words,the present embodiment is able to realize the illumination conditions ofgreat variety in terms of the shape, size, and polarization state of theillumination pupil luminance distribution, by changing each of theshapes and sizes of the first light intensity distribution and thesecond light intensity distribution in mutually different polarizationstates.

As described above, the illumination optical apparatus (2-12) toilluminate the mask M as an illumination target surface on the basis ofthe light from the light source 1 in the present embodiment is able torealize the illumination conditions of great variety in terms of theshape, size, and polarization state of the illumination pupil luminancedistribution. Furthermore, the exposure apparatus (1-WS) of the presentembodiment is able to perform good exposure under an appropriateillumination condition realized according to the pattern characteristicof the mask M, using the illumination optical apparatus (2-12) capableof realizing the illumination conditions of great variety.

In the present embodiment, when the spatial light modulators 33 and 34are in the standard state, the traveling direction of the incident beamto the polarization separating film 35 functioning as a light splitteris parallel to (or coincident with) the traveling direction of theexiting beam from the polarization separating film 36 functioning as alight combiner. In other words, in the standard state of the spatiallight modulators 33 and 34, the traveling directions of the incidentbeam to the spatial light modulation unit 3 and the exiting beam fromthe spatial light modulation unit 3 are coincident with (or parallel to)the optical axis AX of the illumination optical apparatus. Since theoptical paths upstream and downstream of the spatial light modulationunit 3 are coaxial (or parallel), the optical system can be shared, forexample, with the conventional illumination optical apparatus using adiffractive optical element for formation of the illumination pupilluminance distribution.

In the present embodiment, the mirror elements 33 a of the first spatiallight modulator 33 are arranged near the prism member 31 and the mirrorelements 34 a of the second spatial light modulator 34 are arranged nearthe prism member 32. In this case, the prism members 31, 32 serve ascover members for the mirror elements 33 a, 34 a, which can enhance thedurability of the spatial light modulators 33,34.

In the present embodiment, the spatial light modulation unit 3 may be sodesigned that the angle ⊖ of incidence of the light (cf. FIG. 2) to thepolarization separating film 35 formed between the prism members 31 and32 is close to the Brewster's angle. This configuration can reduce thereflectance of p-polarized light on the polarization separating film 35and increase polarization efficiency. The polarization separating films35, 36 are not limited to those made of dielectric multilayer films, butmay be, for example, those having “a polarization separating layer of aperiodic grating structure.” The “polarization separating layer of theperiodic grating structure” of this type can be a wire grid typepolarization separating element in which a plurality of metal gratingsparallel to a first direction are periodically arranged in a seconddirection orthogonal to the first direction. This technology isdisclosed, for example, in Japanese Patent Application Laid-open No.2005-77819 and U.S. Pat. No. 7,116,478 corresponding thereto. Theteachings in U.S. Pat. No. 7,116,478 are incorporated herein byreference.

In the above-described embodiment, the spatial light modulation unit 3is composed of the pair of prism members 31 and 32 and the pair ofspatial light modulators 33 and 34. However, without having to belimited to this, various forms can be contemplated for specificconfigurations of the spatial light modulation unit 3.

In the foregoing embodiment, the afocal lens 4, conical axicon system 6,and zoom lens 7 are arranged in the optical path between the spatiallight modulation unit 3 and the cylindrical micro fly's eye lens 8.However, without having to be limited to this, these optical members canbe replaced, for example, by a condensing optical system functioning asa Fourier transform lens.

In the foregoing embodiment, the p-polarized light having traveled viathe polarization separating film 35 functioning as a light splitter isfolded toward the second spatial light modulator 34 by total reflectionon the interface 32 a between the prism member 32 and the gas 37 as afirst folding surface. Likewise, the p-polarized light having traveledvia the second spatial light modulator 34 is folded toward thepolarization separating film 36 functioning as a light combiner, bytotal reflection on the interface 32 b between the prism member 32 andthe gas 37. However, without having to be limited to this, it is alsopossible to provide a reflecting film on the interfaces 32 a, 32 b.

In the above description, the quadrupolar illumination pupil luminancedistribution is formed by forming the Z-directionally dipolar lightintensity distributional areas 41 a, 41 b by the action of the firstspatial light modulator 33 and forming the X-directionally dipolar lightintensity distributional areas 41 c, 41 d by the action of the secondspatial light modulator 34. However, in the present embodiment, asdescribed above, various forms can be contemplated as to the shape,size, and polarization state of the illumination pupil luminancedistribution. The following will schematically describe an example offorming a pentapolar illumination pupil luminance distribution, withreference to FIG. 5.

In this example, as shown in the left view in FIG. 5, for example, twocircular light intensity distributional areas 42 a and 42 b spaced inthe Z-direction with a center on the optical axis AX and a circularlight intensity distributional area 42 c′ with a center on the opticalaxis AX are formed on the pupil plane of the afocal lens 4 by the actionof the first spatial light modulator 33. The light forming the lightintensity distributional areas 42 a, 42 b, 42 c′ has the polarizationdirection along the X-direction as indicated by double-headed arrows inthe drawing. On the other hand, as shown in the center view in FIG. 5,for example, two circular light intensity distributional areas 42 d and42 e spaced in the X-direction with a center on the optical axis AX anda circular light intensity distributional area 42 c″ with a center onthe optical axis AX are formed on the pupil plane of the afocal lens 4by the action of the second spatial light modulator 34. The lightforming the light intensity distributional areas 42 d, 42 e, 42 c″ hasthe polarization direction along the Z-direction as indicated bydouble-headed arrows in the drawing.

As a result, the light intensity distributional areas 42 a-42 e of thepentapolar shape are formed, as shown in the right view in FIG. 5, onthe pupil plane of the afocal lens 4. The circular light intensitydistributional area 42 c with a center on the optical axis AX is formedby superposition of the light intensity distributional areas 42 e and 42c″. When an optical path length difference of not less than a temporalcoherence length of the light source 1 is provided between thes-polarized light traveling via the first spatial light modulator 33 tothe pupil plane of the afocal lens 4 and the p-polarized light travelingvia the second spatial light modulator 34 to the pupil plane of theafocal lens 4, the beam with the polarization direction along theZ-direction and the beam with the polarization direction along theX-direction as indicated by the double-headed arrows in the drawing passthrough the region of the light intensity distributional area 42 c.

In contrast to it, when there is no path length difference between thes-polarized light traveling via the first spatial light modulator 33 tothe pupil plane of the afocal lens 4 and the p-polarized light travelingvia the second spatial light modulator 34 to the pupil plane of theafocal lens 4, the polarization state of the beam passing through theregion of the light intensity distributional area 42 c coincides withthe polarization state of the incident beam to the spatial lightmodulation unit 3. When the polarization state of the beam incident tothe spatial light modulation unit 3 is circular polarization or 45°linear polarization, the light intensities of the four surrounding lightintensity distributional areas 42 a, 42 b, 42 d, 42 e are equal to eachother and the light intensity of the center light intensitydistributional area 42 c is twice the light intensities of the otherareas.

As another example, light having passed through a half wave plate may bemade incident to the polarization separating film 35 functioning as alight splitter. A ratio of intensities of the s-polarized light and thep-polarized light separated by the polarization separating film 35 canbe controlled by rotating the half wave plate arranged on the lightsource side with respect to the polarization separating film 35, aroundthe optical axis. Namely, it is feasible to control the ratio ofintensities of s-polarized light and p-polarized light reaching thepupil plane of the afocal lens 4. It is also possible to make only thes-polarized light or p-polarized light reach the pupil plane of theafocal lens 4, for example, by controlling the angle of rotation of thehalf wave plate so as to make the s-polarized light incident to thepolarization separating film 35 or by controlling the angle of rotationof the half wave plate so as to make the p-polarized light incident tothe polarization separating film 35. This permits a dipolar lightintensity distribution (e.g., light intensity distributional areas 41 a,41 b in FIG. 4) to be formed on the pupil plane of the afocal lens 4.

In the foregoing embodiment, the polarization separating film 35 locatedon the light splitting surface functions as a light splitter and thepolarization separating film 36 located on the light combining surfaceat the position different from that of the polarization separating film35 functions as a light combiner. However, without having to be limitedto this, it is also possible to adopt a modification example in whichthe light splitter and the light combiner have a common polarizationbeam splitter 51, for example, as shown in FIG. 6. In the spatial lightmodulation unit 3A shown in the modification example of FIG. 6, thes-polarized light reflected on a polarization separating film 51 a, inthe light incident along the optical axis AX into the polarization beamsplitter 51, travels through a quarter wave plate 52 to becomecircularly polarized light, and the circularly polarized light isincident to the first spatial light modulator 53.

Light reflected by a plurality of mirror elements of the first spatiallight modulator 53 travels through the quarter wave plate 52 to becomep-polarized light and the p-polarized light returns to the polarizationbeam splitter 51. The p-polarized light having traveled via the firstspatial light modulator 53 to enter the polarization beam splitter 51,passes through the polarization separating film 51 a to be emitted fromthe polarization beam splitter 51. In the standard state of the firstspatial light modulator 53, the light having traveled along the opticalaxis AX into the spatial light modulation unit 3A and then via the firstspatial light modulator 53 is emitted along the optical axis AX from thespatial light modulation unit 3A.

On the other hand, the p-polarized light passing through thepolarization separating film 51 a of the polarization beam splitter 51travels through a quarter wave plate 54 to become circularly polarizedlight, and the circularly polarized light is incident to the secondspatial light modulator 55. Light reflected by a plurality of mirrorelements of the second spatial light modulator 55 travels through thequarter wave plate 54 to become s-polarized light and the s-polarizedlight returns to the polarization beam splitter 51. The s-polarizedlight having traveled via the second spatial light modulator 55 andhaving entered the polarization beam splitter 51, is reflected by thepolarization separating film 51 a and the reflected light is emittedfrom the polarization beam splitter 51. In the standard state of thesecond spatial light modulator 55, the light having traveled along theoptical axis AX into the spatial light modulation unit 3A and then viathe second spatial light modulator 55, is emitted along the optical axisAX from the spatial light modulation unit 3A.

In the above description, the spatial light modulators with theplurality of optical elements arranged two-dimensionally and controlledindividually are those in which the orientations of the reflectingsurfaces (angles: inclinations) arranged two-dimensionally can beindividually controlled. However, without having to be limited to this,it is also possible, for example, to use spatial light modulators inwhich heights (positions) of the reflecting surfaces arrangedtwo-dimensionally can be individually controlled. The spatial lightmodulators of this type applicable herein can be selected, for example,from the spatial light modulators disclosed in Japanese PatentApplication Laid-open No. 6-281869 and U.S. Pat. No. 5,312,513corresponding thereto, and in FIG. 1d in Japanese Patent ApplicationLaid-open (Translation of PCT Application) No. 2004-520618 and U.S. Pat.No. 6,885,493 corresponding thereto. These spatial light modulators areable to apply the same action as a diffracting surface, to the incidentlight by forming a two-dimensional height distribution. Theabove-described spatial light modulators with the plurality ofreflecting surfaces arranged two-dimensionally may be modified, forexample, according to the disclosure in Japanese Patent ApplicationLaid-open (Translation of PCT Application) No. 2006-513442 and U.S. Pat.No. 6,891,655 corresponding thereto, or according to the disclosure inJapanese Patent Application Laid-open (Translation of PCT Application)No. 2005-524112 and U.S. Pat. Published Application No. 2005/0095749corresponding thereto. The teachings in U.S. Pat. No. 5,312,513, U.S.Pat. No. 6,885,493, U.S. Pat. No. 6,891,655, and U.S. Pat. PublishedApplication No. 2005/0095749 are incorporated herein by reference.

In the above description, the spatial light modulators used are thereflective spatial light modulators with the plurality of mirrorelements, but, without having to be limited to this, it is alsopossible, for example, to use the transmissive spatial light modulatordisclosed in U.S. Pat. No. 5,229,872. The teachings in U.S. Pat. No.5,229,872 are incorporated herein by reference. FIG. 7 schematicallyshows a configuration of a spatial light modulation unit according to amodification example having transmissive spatial light modulators. Inthe spatial light modulation unit 3B shown in the modification exampleof FIG. 7, the s-polarized light reflected by a polarization separatingfilm 61 a, in light incident along the optical axis AX to a polarizationbeam splitter 61 functioning as a light splitter, is incident into afirst spatial light modulator 62.

The light having passed through a plurality of optical elements (prismelements or the like) of the first spatial light modulator 62 is foldedby a path folding mirror 63 and thereafter the folded light is incidentto a polarization beam splitter 64 functioning as a light combiner. Thes-polarized light having traveled via the first spatial light modulator62 and having entered the polarization beam splitter 64 is reflected bya polarization separating film 64 a and the reflected light is emittedfrom the polarization beam splitter 64. In the standard state of thefirst spatial light modulator 62, the light having traveled along theoptical axis AX into the spatial light modulation unit 3B and thenthrough the first spatial light modulator 62 is emitted along theoptical axis AX from the spatial light modulation unit 3B.

The p-polarized light having passed through the polarization separatingfilm 61 a of the polarization beam splitter 61 is incident into a secondspatial light modulator 65. The light having passed through a pluralityof optical elements of the second spatial light modulator 65 is foldedby a path folding mirror 66 and the folded light is incident to thepolarization beam splitter 64. The p-polarized light having traveled viathe second spatial light modulator 65 and having entered thepolarization beam splitter 64, travels through the polarizationseparating film 64 a and is emitted from the polarization beam splitter64. In the standard state of the second spatial light modulator 65, thelight having traveled along the optical axis AX into the spatial lightmodulation unit 3B and then through the second spatial light modulator65 is emitted along the optical axis AX from the spatial lightmodulation unit 3B.

In the above description, the optical system is so configured that thelight from the light source 1 supplying the light in the polarizationstate in which linearly polarized light is a principal component, isguided to the spatial light modulation unit (3; 3A; 3B) whilesubstantially maintaining the polarization state of the light, but it isalso possible, for example, to adopt a modification example in which apolarization control unit 13 for making the polarization state ofexiting light variable is provided in the optical path on the lightsource 1 side of the spatial light modulation unit 3, as shown in FIG.8. In FIG. 8 the members with the same functionality as in FIG. 1 aredenoted by the same reference symbols.

The polarization control unit 13 shown in the modification example ofFIG. 8 receives the light from the light source 1 having traveled viathe shaping optical system 2 and path folding mirror, and emits light ina desired polarization state toward the spatial light modulation unit 3.This polarization control unit 13 is composed, for example, of a halfwave plate 13 a arranged as rotatable around the optical axis or aroundan axis parallel to the optical axis, and a rotational drive unit 13 bwhich rotationally drives the half wave plate 13 a.

For example, linearly polarized light with the polarization direction(direction of the electric field) along the 45° direction to the x-axisor the Z-axis in the XZ plane can be supplied to the spatial lightmodulation unit 3, by rotationally adjusting the half wave plate 13 athrough the rotational drive unit 13 b. At this time, the light quantityof the s-polarized light (the light traveling toward the first spatiallight modulator 33) and the light quantity of the p-polarized light (thelight traveling toward the second spatial light modulator 34) separatedby the polarization separating film of the spatial light modulation unit3 become approximately equal.

By the rotational adjustment of the half wave plate 13 a in thepolarization control unit 13, it is feasible to set the ratio of thelight quantities of the s-polarized light (the light toward the firstspatial light modulator 33) and the p-polarized light (the light towardthe second spatial light modulator 34) separated by the polarizationseparating film of the spatial light modulation unit 3, to any lightquantity ratio. For example, in the case where the quadrupolar lightintensity distributional areas 41 a-41 d as shown in FIG. 4 are formed,a ratio of the light intensity of the two light intensity distributionalareas 41 a, 41 b spaced in the Z-direction with a center on the opticalaxis AX and the light intensity of the two light intensitydistributional areas 41 c, 41 d spaced in the x-direction with a centeron the optical axis AX can be set at a desired light quantity ratio.

In the modification example shown in FIG. 8, the apparatus may be soarranged that an illumination pupil polarization distribution ismeasured by a pupil polarization distribution measuring device 14 andthat the polarization control unit 13 is controlled according to theresult of the measurement. In this case, each spatial light modulator inthe spatial light modulation unit may be controlled as occasion maydemand. This pupil polarization distribution measuring device 14 is adevice that is provided in the wafer stage WS for holding the wafer W orin a measurement stage provided separately from the wafer stage WS, andthat measures the polarization state in the pupil (or in the aperture)of the illumination light (exposure light) incident to the wafer W. Thedetailed configuration and action of the polarization state measuringdevice 14 are disclosed, for example, in Japanese Patent ApplicationLaid-open No. 2005-5521. The teachings in Japanese Patent ApplicationLaid-open No. 2005-5521 are incorporated herein by reference.

This configuration is effective as follows: for example, even when thereis a reflectance difference between polarizations in each path foldingmirror arranged in the illumination optical system or in the projectionoptical system, adverse effect thereby can be prevented. In themodification example of FIG. 8 the direction of polarization to thespatial light modulation unit 3 is adjusted by the polarization controlunit 13, but the same effect can also be achieved by rotating the lightsource 1 itself or the spatial light modulation unit 3 around theoptical axis. This polarization control unit 13 can also be applied tothe modification examples shown in FIGS. 6 and 7.

In the aforementioned embodiment and the modification examples of FIGS.6 to 8, the light splitter and the light combiner have the polarizationseparating film (35, 36; 51 a; 61 a, 64 a), but, without having to belimited to this, it is also possible to adopt a configuration in whichthe light splitter and the light combiner have a separating film toeffect amplitude division of a beam. In this case, the first lightintensity distribution formed on the illumination pupil by the action ofthe first spatial light modulator has the same polarization state as thesecond light intensity distribution formed on the illumination pupil bythe action of the second spatial light modulator, but it becomesfeasible to realize illumination conditions of great variety in terms ofthe shape and size of the illumination pupil luminance distribution, bychanging each of the shapes and sizes of the first light intensitydistribution and the second light intensity distribution.

In the aforementioned embodiment and the modification examples of FIGS.6 to 8, the polarization separating film (35; 51 a; 61 a) is used tosplit the incident beam into two beams, but, without having to belimited to this, it is also possible, for example, to adopt aconfiguration in which a diffractive optical element is used to splitthe incident beam into two beams. FIG. 9 is a drawing schematicallyshowing a major configuration of a modification example using adiffractive optical element as a light splitter. The modificationexample of FIG. 9 has a configuration in which the spatial lightmodulation unit 3 in the embodiment of FIG. 1 is replaced by adiffractive optical element 71, a condenser lens 72, a pair of half waveplates 73A, 73B, and a pair of spatial light modulation units 74A, 74B.

In the modification example of FIG. 9, the beam from the light source 1having traveled through the shaping optical system 2 is incident alongthe optical axis AX to the diffractive optical element 71 as a lightsplitter. The diffractive optical element 71 has such a function that,for example, when a parallel beam with a rectangular cross section isincident along the optical axis AX thereto, it forms two rectangularlight intensity distributional areas spaced in the Z-direction with acenter on the optical axis AX, in its far field (or Fraunhoferdiffraction region). In other words, the diffractive optical element 71functions to split the incident light into two beams.

The first beam out of the two beams split by the diffractive opticalelement 71 travels through the condenser lens 72 functioning as aFourier transform lens and then enters the half wave plate 73A rotatablearound the optical axis AXa of the optical path of the first beam oraround an axis parallel to the optical axis AXa. Light in a linearlypolarized state having passed through the half wave plate 73A travelsvia the spatial light modulation unit 74A and thereafter travels throughthe front lens unit 4 a of the afocal lens 4 to reach the pupil plane 4c of the afocal lens 4. On the other hand, the second beam out of thetwo beams split by the diffractive optical element 71 travels throughthe condenser lens 72 and enters the half wave plate 73B rotatablearound the optical axis AXb of the optical path of the second beam oraround an axis parallel to the optical axis AXb. Light in a linearlypolarized state having passed through the half wave plate 73B travelsvia the spatial light modulation unit 74B and thereafter travels throughthe front lens unit 4 a of the afocal lens 4 to reach the pupil plane 4c. The front lens unit 4 a of the afocal lens 4 is an optical systemwhich superimposes the beam having passed via the spatial lightmodulator in the spatial light modulation unit 74A and the beam havingpassed via the spatial light modulator in the spatial light modulationunit 74B, on the pupil plane. 4 c, and functions as a light combiner.

For brevity of description, it is assumed hereinafter that the spatiallight modulation unit 74A arranged in the optical path of the first beamand the spatial light modulation unit 74B arranged in the optical pathof the second beam have the same configuration. It is also assumed thata parallel beam in a linearly polarized state with the polarizationdirection along a direction at 45° to the Z-direction and theX-direction is incident to the diffractive optical element 71, thatlight in an X-directionally linearly polarized state (laterallypolarized state) with polarization along the X-direction is incident tothe spatial light modulation unit 74A because of the action of the halfwave plate 73A, and that light in a Z-directionally linearly polarizedstate (vertically polarized state) with polarization along theZ-direction is incident to the spatial light modulation unit 74B becauseof the action of the half wave plate 73B.

The specific configuration and action of the spatial light modulationunit 74A will be described below with reference to FIGS. 10 and 11.Since the spatial light modulation unit 74B basically has the sameconfiguration as the spatial light modulation unit 74A, redundantdescription is omitted about the specific configuration and action ofthe spatial light modulation unit 74B. The spatial light modulation unit74A, as shown in FIG. 10, has a prism 23 b made of an optical material,e.g., fluorite, and a reflective spatial light modulator 23 a attachedin proximity to a side face 23 ba of the prism 23 b parallel to the XYplane. The optical material for making the prism 23 b does not have tobe limited to fluorite, but may be silica or any other optical materialaccording to the wavelength of the light supplied from the light source1.

The prism 23 b has a form obtained by replacing one side face of arectangular parallelepiped (a side face opposed to the side face 23 bato which the spatial light modulator 23 a is attached in proximity) byside faces 23 bb and 23 bc depressed in a V-shape, and is also called aK prism because of the sectional shape along the YZ plane. The sidefaces 23 bb and 23 bc depressed in the V-shape in the prism 23 b aredefined by two planes PNI and PN2 intersecting at an obtuse angle. Thetwo planes PNI and PN2 both are orthogonal to the YZ plane and make theV-shape along the YZ plane.

Internal surfaces of the two side faces 23 bb and 23 bc in contact alongan intersecting line (straight line extending in the X-direction) P3between the two planes PNI and PN2 function as reflecting surfaces R1and R2. Namely, the reflecting surface RI is located on the plane PN1,the reflecting surface R2 is located on the plane PN2, and an anglebetween the reflecting surfaces R1 and R2 is an obtuse angle. As anexample, the angles can be determined as follows: the angle between thereflecting surfaces R1 and R2 is 120′; the angle between the entrancesurface IP of the prism 23 b perpendicular to the optical axis AXa, andthe reflecting surface R1 is 60′; the angle between the exit surface OPof the prism 23 b perpendicular to the optical axis AXa, and thereflecting surface R2 is 60°.

In the prism 23 b, the side face 23 ba to which the spatial lightmodulator 23 a is attached in proximity is parallel to the optical axisAXa; and the reflecting surface R1 is located on the light source 1 side(on the upstream side of the exposure apparatus; on the left in FIG. 10)and the reflecting surface R2 is located on the afocal lens 4 side (onthe downstream side of the exposure apparatus; on the right in FIG. 10).More specifically, the reflecting surface R1 is obliquely arranged withrespect to the optical axis AXa and the reflecting surface R2 isobliquely arranged with respect to the optical axis AXa and in symmetrywith the reflecting surface R1 with respect to a plane passing theintersecting line P3 and being parallel to the xz plane. The side face23 ba of the prism 3 b is an optical surface opposed to a surface onwhich the plurality of mirror elements SE of the spatial light modulator23 a are arranged, as described below.

The reflecting surface R1 of the prism 23 b reflects the light incidentthrough the entrance surface IP, toward the spatial light modulator 23a. The spatial light modulator 23 a is located in the optical pathbetween the reflecting surface R1 and the reflecting surface R2 andreflects the light incident via the reflecting surface R1. Thereflecting surface R2 of the prism 23 b reflects the light incident viathe spatial light modulator 23 a to guide the reflected light throughthe exit surface OP to the front lens unit 4 a of the afocal lens 4. InFIG. 10, the optical paths are expanded so that the optical axis AXaextends linearly on the rear side of the spatial light modulation unit74A, for easier understanding of description. FIG. 10 shows the examplewherein the prism 23 b is integrally made of one optical block, but theprism 23 b may be constructed using a plurality of optical blocks.

The spatial light modulator 23 a applies spatial modulation according toa position of incidence of light, to the light incident via thereflecting surface R1. The spatial light modulator 23 a is provided witha plurality of micro mirror elements (optical elements) SE arrangedtwo-dimensionally, as shown in FIG. 11. F or easier description andillustration, FIGS. 10 and 11 show a configuration example in which thespatial light modulator 23 a has sixteen mirror elements SE of a 4×4matrix, but the spatial light modulator actually has a much largernumber of mirror elements than sixteen elements.

With reference to FIG. 10, among a bundle of rays incident along adirection parallel to the optical axis AXa into the spatial lightmodulation unit 23, a ray L1 is incident to a mirror element SEa out ofthe plurality of mirror elements SE, and a ray L2 is incident to amirror element SEb different from the mirror element SEa. Similarly, aray L3 is incident to a mirror element SEc different from the mirrorelements SEa, SEb and a ray L4 is incident to a mirror element SEddifferent from the mirror elements Sea SEc. The mirror elements SEa-SEdapply respective spatial modulations set according to their positions,to the rays LI-L4, respectively.

The spatial light modulation unit 23 is so configured that in thestandard state in which the reflecting surfaces of all the mirrorelements SE of the spatial light modulator 23 a are set in parallel withthe XY plane, the rays incident along a direction parallel to theoptical axis AXa to the reflecting surface R1 travel via the spatiallight modulator 23 a and thereafter are reflected to a directionparallel to the optical axis AXa by the reflecting surface R2.Furthermore, the spatial light modulation unit 23 is so configured thatan air equivalent length from the entrance surface IP of the prism 23 bvia the mirror elements SEa-SEd to the exit surface OP is equal to anair-equivalent length from the position corresponding to the entrancesurface IP to the position corresponding to the exit surface OP withoutthe prism 23 b in the optical path. An air-equivalent length herein isobtained by converting an optical path length in an optical system intoan optical path length in air having the refractive index of 1, and anair-equivalent length in a medium having the refractive index n isobtained by multiplying an optical path length therein by l/n.

The surface in which the plurality of mirror elements SE of the spatiallight modulator 23 a are arrayed is positioned at or near the rear focalpoint of the condenser lens 72 and positioned at or near the front focalpoint of the afocal lens 4. Therefore, a beam having a cross section ofa shape according to the characteristic of the diffractive opticalelement 71 (e.g., a rectangular shape) is incident to the spatial lightmodulator 23 a. The light reflected by the mirror elements SEaSEd of thespatial light modulator 23 a and provided with a predetermined angledistribution forms predetermined light intensity distributional areas SPI-SP4 on the pupil plane 4 c of the afocal lens 4. Namely, the frontlens unit 4 a of the afocal lens 4 converts angles given to the exitinglight by the mirror elements SEa-SEd of the spatial light modulator 23a, into positions on the plane 4 c being a far field region (Fraunhoferdiffraction region) of the spatial light modulator 23 a.

With reference to FIG. 1, the entrance surface of the cylindrical microfly's eye lens 8 is positioned at or near a position optically conjugatewith the pupil plane 4 c (not shown in FIG. 1) of the afocal lens 4.Therefore, the light intensity distribution (luminance distribution) ofthe secondary light source formed by the cylindrical micro fly's eyelens 8 is a distribution according to the light intensity distributionalareas SPI-SP4 formed on the pupil plane 4 c by the spatial lightmodulator 23 a and the front lens unit 4 a of the afocal lens 4. Thespatial light modulator 23 a is a movable multi-mirror including themirror elements SE being a large number of micro reflecting elementsarranged regularly and two-dimensionally along one plane with areflecting surface of a planar shape up, as shown in FIG. 11.

Each mirror element SE is movable and an inclination of the reflectingsurface thereof, i.e., an angle and direction of inclination of thereflecting surface, is independently controlled by the action of thedrive unit 23 c (not shown in FIG. 11) operating according to commandsfrom the control unit (not shown). Each mirror element SE can becontinuously or discretely rotated by a desired angle of rotation aroundeach of axes of rotation along two directions (X-direction andY-direction) orthogonal to each other and parallel to the reflectingsurface. Namely, inclinations of the reflecting surfaces of therespective mirror elements SE can be controlled two-dimensionally.

In a case where the reflecting surface of each mirror element SE isdiscretely rotated, a preferred switch control is such that the angle ofrotation is switched in multiple stages (e.g., . . . , −2.5°, −2.0°, . .. , 0°, +0.5°, . . . , +2.5°, . . . ). FIG. 11 shows the mirror elementsSE with the contour of the square shape, but the contour of the mirrorelements SE is not limited to the square. However, the contour may be ashape permitting arrangement of the mirror elements SE with a gap assmall as possible (a shape permitting closest packing), from theviewpoint of efficiency of utilization of light. Furthermore, thespacing between two adjacent mirror elements SE may be minimumnecessary, from the viewpoint of the light utilization efficiency.

In the spatial light modulator 23 a, the postures of the respectivemirror elements SE are changed by the action of the drive unit 23 coperating according to control signals from the control unit, wherebyeach mirror element SE is set in a predetermined orientation. The raysreflected at respective predetermined angles by the mirror elements SEof the spatial light modulator 23 a travel through the afocal lens 4 andzoom lens 7 to form a light intensity distribution (illumination pupilluminance distribution) of a multi-polar shape (quadrupolar, pentapolar,. . . ) or another shape on the rear focal point of the cylindricalmicro fly's eye lens 8 or on the illumination pupil near it. Thisillumination pupil luminance distribution varies similarly(isotropically) by the action of the zoom lens 7.

Specifically, laterally polarized light reflected at respectivepredetermined angles by the mirror elements SE of the spatial lightmodulator 23 a in the spatial light modulation unit 74A forms, forexample, two circular light intensity distributional areas 41 a and 41 bspaced in the Z-direction with a center on the optical axis AX, on thepupil plane 4 c of the afocal lens 4, as shown in FIG. 4. The lightforming the light intensity distributional areas 41 a and 41 b has thepolarization direction along the X-direction as indicated bydouble-headed arrows in the drawing.

Similarly, vertically polarized light reflected at respectivepredetermined angles by the mirror elements of the spatial lightmodulator in the spatial light modulation unit 74B forms, for example,two circular light intensity distributional areas 41 c and 41 d spacedin the X-direction with a center on the optical axis AX, on the pupilplane 4 c of the afocal lens 4, as shown in FIG. 4. The light formingthe light intensity distributional areas 41 c and 41 d has thepolarization direction along the Z-direction as indicated bydouble-headed arrows in the drawing.

The light forming the quadrupolar light intensity distribution 41 on thepupil plane 4 c of the afocal lens 4 forms quadrupolar light intensitydistributional areas corresponding to the light intensity distributionalareas 41 a-41 d, on the entrance surface of the cylindrical micro fly'seye lens 8, and on the rear focal plane of the cylindrical micro fly'seye lens 8 or on the illumination pupil near it (the position where theaperture stop 9 is arranged). Furthermore, quadrupolar light intensitydistributional areas corresponding to the light intensity distributionalareas 41 a-41 d are also formed at other illumination pupil positionsoptically conjugate with the aperture stop 9, i.e., at the pupilposition of the imaging optical system 12 and at the pupil position ofthe projection optical system PL.

In another example, the spatial light modulation unit 74A acts, forexample, to form two circular light intensity distributional areas 42 aand 42 b spaced in the Z-direction with a center on the optical axis AX,and a circular light intensity distributional area 42 c′ with a centeron the optical axis AX, as shown in the left view in FIG. 5, on thepupil plane 4 c of the afocal lens 4. The light forming the lightintensity distributional areas 42 a, 42 b, 42 c′ has the polarizationdirection along the X-direction as indicated by double-headed arrows inthe drawing. On the other hand, the spatial light modulation unit 74Bacts, for example, to form two circular light intensity distributionalareas 42 d and 42 e spaced in the X-direction with a center on theoptical axis AX, and a circular light intensity distributional area 42c″ with a center on the optical axis AX, as shown in the center view inFIG. 5, on the pupil plane 4 c of the afocal lens 4. The light formingthe light intensity distributional areas 42 d, 42 e, 42 c″ has thepolarization direction along the Z-direction as indicated bydouble-headed arrows in the drawing.

As a consequence, the light intensity distributional areas 42 a-42 e ofthe pentapolar shape are formed on the pupil plane 4 c of the afocallens 4, as shown in the right view in FIG. 5. The circular lightintensity distributional area 42 c with a center on the optical axis AXis formed by superposition of the light intensity distributional areas42 c′ and 42 c″. When an optical path length difference of not less thanthe temporal coherence length of the light source 1 is provided betweenthe horizontally polarized light having traveled via the spatial lightmodulation unit 74A to reach the pupil plane 4 c of the afocal lens 4and the vertically polarized light having traveled via the spatial lightmodulation unit 74B to reach the pupil plane of the afocal lens 4, thebeam with the polarization direction along the Z-direction and the beamwith the polarization direction along the X-direction pass through theregion of the light intensity distributional area 42 c, as indicated bythe double-headed arrows in the drawing.

In the modification example of FIG. 9, as described above, it isfeasible to freely and quickly change the illumination pupil luminancedistribution consisting of the first light intensity distribution in thelaterally polarized state formed on the pupil plane by the action of thespatial light modulator in the spatial light modulation unit 74A and thesecond light intensity distribution in the vertically polarized stateformed on the pupil plane by the action of the spatial light modulatorin the spatial light modulation unit 74B. In other words, themodification example of FIG. 9 is also able to realize the illuminationconditions of great variety in terms of the shape, size, andpolarization state of the illumination pupil luminance distribution, bychanging each of the shapes and sizes of the first light intensitydistribution and the second light intensity distribution in mutuallydifferent polarization states, as in the embodiment of FIG. 1.

Since the modification example of FIG. 9 uses the diffractive opticalelement 71 as a light splitter, it has the advantage that an improvementcan be made in evenness of the intensity of light incident to thespatial light modulators in the spatial light modulation units 74A, 74B.Since there is no variation in angles of the beams immediately after thediffractive optical element 71 even when the position of the beamincident to the diffractive optical element 71 varies, the modificationexample has the advantage that the positions of the beams incident tothe spatial light modulators in the spatial light modulation units 74A,74B are unlikely to vary.

In the modification example of FIG. 9, where a beam with a rectangularcross section is incident to the diffractive optical element 71, theincident beam may be split in the shorter-side direction of therectangular cross section, in order to miniaturize the prism 23 b and,therefore, miniaturize the spatial light modulation units 74A and 74B.In other words, the incident beam may be split in a plane a normal towhich is a longitudinal direction of effective regions of the spatiallight modulators in the spatial light modulation units 74A, 74B. Ingeneral, where the incident light has a sectional shape in which alength along a first direction in the cross section of the incident beamto the diffractive optical element 71 is smaller than a length along asecond direction perpendicular to the first direction, the spatial lightmodulation units 74A and 74B can be compactified by splitting theincident beam along the first direction.

In the modification example of FIG. 9, the diffractive optical element71 is used to split the incident beam into two beams. However, withouthaving to be limited to this, it is also possible to adopt aconfiguration of splitting the incident beam into two beams by use of aprism unit 76 having a pair of prism members 76 a and 76 b, for example,as shown in FIG. 12. The modification example of FIG. 12 has theconfiguration similar to the modification example of FIG. 9, but isdifferent from the modification example of FIG. 9 only in that the prismunit 76 is arranged instead of the diffractive optical element 71 andthe condenser lens 72. In FIG. 12, the elements with the samefunctionality as the constituent elements shown in FIG. 9 are denoted bythe same reference symbols as those in FIG. 9. Since the modificationexample shown in FIG. 12 uses the prism unit 76 having the pair of prismmembers 76 a and 76 b, to split the incident beam into two beams, itbecomes feasible to miniaturize the apparatus.

The prism unit 76 functioning as a light splitter in the modificationexample of FIG. 12 is composed of the following members arranged in theorder named from the light source side (from the left in the drawing):first prism member 76 a with a plane on the light source side and with arefracting surface of a concave and V-shape on the mask side (on theright in the drawing); and second prism member 76 b with a plane on themask side and with a refracting surface of a convex and V-shape on thelight source side. The concave refracting surface of the first prismmember 76 a is composed of two planes and an intersecting line (ridgeline) between them extends along the X-direction. The convex refractingsurface of the second prism member 76 b is formed so as to becomplementary to the concave refracting surface of the first prismmember 76 a. Specifically, the convex refracting surface of the secondprism member 76 b is also composed of two planes and an intersectingline (ridge line) between them extends along the X-direction. In themodification example of FIG. 12, the prism unit 76 as a light splitteris composed of the pair of prism members 76 a and 76 b, but it is alsopossible to construct the light splitter of at least one prism.Furthermore, it is possible to contemplate various forms for specificconfigurations of the light splitter.

In the modification example of FIG. 9 and the modification example ofFIG. 12, each of the half wave plates 73A and 73B is provided in theoptical path between the condenser lens 72 and the spatial lightmodulation units 74A and 74B. However, without having to be limited tothis, the half wave plates 73A and 73B can also be located at anotherappropriate position in the optical path of the first beam and atanother appropriate position in the optical path of the second beam outof the two beams split by the diffractive optical element 71 or by theprism unit 76.

In the modification example of FIG. 9 and the modification example ofFIG. 12, the half wave plate 73A rotatable around the predetermined axisis provided in the optical path of the first beam and the half waveplate 73B rotatable around the predetermined axis is provided in theoptical path of the second beam. However, without having to be limitedto this, it is also possible to adopt a configuration wherein a halfwave plate is provided so as to be rotatable around a predetermined axisor stationary, in at least one optical path, or a configuration whereina polarizer or an optical rotator other than the half wave plate isprovided so as to be rotatable around a predetermined axis orstationary, in at least one optical path.

The half wave plate (polarizer or optical rotator in general) may bearranged as detachable from the optical path so that it can be retractedfrom the optical path when not needed, which can lengthen the life ofthe half wave plate. Similarly, the half wave plate (polarizer oroptical rotator in general) can be arranged as replaceable with a glasssubstrate having the same path length, which can also lengthen the lifeof the half wave plate.

When a quarter wave plate rotatable around a predetermined axis isarranged in addition to the half wave plate, elliptically polarizedlight can be controlled into desired linearly polarized light. Adepolarizer (depolarizing element) can also be used in addition to orinstead of the half wave plate, whereby the light can be obtained in adesired unpolarized state. It is also possible, for example, to insert aplane-parallel plate of a required thickness in one optical path so asto provide the path length difference of not less than the temporalcoherence length between the first beam and the second beam as describedabove, whereby a beam passing through the same region on theillumination pupil can be depolarized. Furthermore, when the opticalpath length difference of not less than the temporal coherence length isprovided between the first beam and the second beam, speckle 20 can bereduced by about √(½).

Since the illumination optical apparatus according to the embodiment andmodification examples uses the optical unit (spatial light modulationunit) with the pair of spatial light modulators in which the postures ofthe mirror elements are individually varied, it is feasible to freelyand quickly change the illumination pupil luminance distributionconsisting of the first light intensity distribution in the firstpolarization state formed on the illumination pupil by the action of thefirst spatial light modulator and the second light intensitydistribution in the second polarization state formed on the illuminationpupil by the action of the second spatial light modulator. In otherwords, by changing each of the shapes and sizes of the first lightintensity distribution and the second light intensity distribution inmutually different polarization states, it is feasible to realize theillumination conditions of great variety in terms of the shape, size,and polarization state of the illumination pupil luminance distribution.

In this manner, the illumination optical apparatus according to theembodiment and the modification examples is able to realize theillumination conditions of great variety in terms of the shape, thesize, and the polarization state of the illumination pupil luminancedistribution. Furthermore, the exposure apparatus according to theembodiment and modification examples is able to perform good exposureunder an appropriate illumination condition realized according to apattern characteristic of a mask M, using the illumination opticalapparatus capable of realizing the illumination conditions of greatvariety, and, therefore, to manufacture good devices.

In the above-described embodiment and each modification example, theapparatus may also be configured as follows: a pupil luminancedistribution measuring device is used to measure the illumination pupilluminance distribution during formation of the illumination pupilluminance distribution by means of the spatial light modulation unit andeach spatial light modulator in the spatial light modulation unit iscontrolled according to the result of the measurement. Such technologyis disclosed, for example, in Japanese Patent Application Laid-open No.2006-54328, and Japanese Patent Application Laid-open No. 2003-22967 andU.S. Pat. Published Application No. 2003/0038225 corresponding thereto.The teachings in U.S. Pat. Published Application No. 2003/0038225 areincorporated herein by reference.

In the aforementioned embodiment, the mask can be replaced by a variablepattern forming device which forms a predetermined pattern on the basisof predetermined electronic data. The use of this variable patternforming device minimizes the effect on synchronization accuracy evenwhen the pattern surface is vertical. The variable pattern formingdevice applicable herein can be, for example, a DMD (Digital MicromirrorDevice) including a plurality of reflecting elements driven based onpredetermined electronic data. The exposure apparatus using DMD isdisclosed, for example, in Japanese Patent Application Laid-open No.2004-304135 and International Publication WO2006/080285 and U.S. Pat.Published Application No. 2007/0296936 corresponding thereto. Besidesthe reflective spatial light modulators of the non-emission type likeDMD, it is also possible to use transmissive spatial light modulators orto use self-emission type image display devices. The variable patternforming device may also be used in cases where the pattern surface ishorizontal. The teachings in U.S. Pat. Published Application No.2007/0296936 are incorporated herein by reference.

The exposure apparatus according to the foregoing embodiment ismanufactured by assembling various sub-systems containing theirrespective components as set forth in the scope of claims in the presentapplication, so as to maintain predetermined mechanical accuracy,electrical accuracy, and optical accuracy. F or ensuring these variousaccuracies, the following adjustments are carried out before and afterthe assembling: adjustment for achieving the optical accuracy forvarious optical systems; adjustment for achieving the mechanicalaccuracy for various mechanical systems; adjustment for achieving theelectrical accuracy for various electrical systems. The assemblingblocks from the various sub-systems into the exposure apparatus includemechanical connections, wire connections of electric circuits, pipeconnections of pneumatic circuits, etc. between the various sub-systems.It is needless to mention that there are assembling blocks of theindividual sub-systems, before the assembling blocks from the varioussub-systems into the exposure apparatus. After completion of theassembling blocks from the various sub-systems into the exposureapparatus, overall adjustment is carried out to ensure variousaccuracies as the entire exposure apparatus. The manufacture of exposureapparatus is desirably performed in a clean room in which thetemperature, cleanliness, etc. are controlled.

The following will describe a device manufacturing method using theexposure apparatus of the above embodiment. FIG. 13 is a flowchartshowing manufacturing blocks of semiconductor devices. As shown in FIG.13, the manufacturing blocks of semiconductor devices include depositinga metal film on a wafer W to become a substrate for semiconductordevices (block S40); and applying a photoresist as a photosensitivesubstrate onto the deposited metal film (block S42). The subsequentblocks include transferring a pattern formed on a mask (reticle) M, intoeach shot area on the wafer W, using the projection exposure apparatusof the above embodiment (block S44: exposure block); and performingdevelopment of the wafer W after completion of the transfer, i.e.,development of the photoresist onto which the pattern has beentransferred (block S46: development block). A block subsequent theretois to process the surface of the wafer W by etching or the like, usingthe resist pattern made on the surface of the wafer W in block S46, as amask (block S48: processing block).

The resist pattern herein is a photoresist layer in which projectionsand depressions are formed in the shape corresponding to the patterntransferred by the projection exposure apparatus of the aboveembodiment, and which the depressions penetrate throughout. In the blockS48, the surface of the wafer W is processed through this resistpattern. The processing carried out in the block S48 includes, forexample, at least either etching of the surface of the wafer W ordeposition of a metal film or the like. In the block S44, the projectionexposure apparatus of the above embodiment performs the transfer of thepattern using the wafer W coated with the photoresist, as aphotosensitive substrate or plate P.

FIG. 14 is a flowchart showing manufacturing blocks of a liquid crystaldevice such as a liquid-crystal display device. As shown in FIG. 14,manufacturing blocks of the liquid crystal device include sequentiallycarrying out a pattern forming block (block S50), a color filter formingblock (block S52), a cell assembly block (block S54), and a moduleassembly block (block S56).

The pattern forming block of block S50 is to form a predeterminedpattern such as a circuit pattern and an electrode pattern on a glasssubstrate coated with a photoresist, as a plate P, using the projectionexposure apparatus of the above embodiment. This pattern forming blockincludes an exposure block of transferring a pattern onto a photoresistlayer by means of the projection exposure apparatus of the aboveembodiment; a development block of developing the plate P after thetransfer of the pattern, i.e., developing the photoresist layer on theglass substrate, to make the photoresist layer in the shapecorresponding to the pattern; and a processing block of processing thesurface of the glass substrate through the developed photoresist layer.

The color filter forming block of block S52 is to form a color filter ina configuration wherein a large number of sets of three dotscorresponding to R (Red), G (Green), and B (Blue) are arrayed in amatrix pattern, or in a configuration wherein a plurality of sets ofthree stripe filters of R, G, and B are arrayed in a horizontal scandirection.

The cell assembly block of block S54 is to assemble a liquid crystalpanel (liquid crystal cell) using the glass substrate with thepredetermined pattern thereon in block S50 and the color filter formedin block S52. Specifically, the liquid crystal panel is formed, forexample, by pouring a liquid crystal into between the glass substrateand the color filter. The module assembly block of block S56 is toattach various components such as electric circuits and backlights fordisplay operation of this liquid crystal panel, to the liquid crystalpanel assembled in block S54.

Embodiments of the present invention IS not limited to the applicationto the exposure apparatus for manufacture of semiconductor devices, butcan also be widely applied, for example, to the exposure apparatus fordisplay devices such as liquid-crystal display devices formed withrectangular glass plates, or plasma displays and to the exposureapparatus for manufacture of various devices such as imaging devices(CCDs or the like), micromachines, thin-film magnetic heads, and DNAchips. Furthermore, embodiments of the present invention can also beapplied to the exposure block (exposure apparatus) in manufacture ofmasks (photomasks, reticles, etc.) with mask patterns of various devicesby photolithography.

The aforementioned embodiment used the ArF excimer laser light (thewavelength: 193 nm) or the KrF excimer laser light (the wavelength: 248nm) as the exposure light, but the exposure light does not have to belimited to these: embodiments of the present invention can also beapplied to any other appropriate laser light source, e.g., an F2 laserlight source which supplies the laser light at the wavelength of 157 nm.

In the foregoing embodiment, it is also possible to apply a technique offilling the interior of the optical path between the projection opticalsystem and the photosensitive substrate with a medium having therefractive index larger than 1.1 (typically, a liquid), which is socalled a liquid immersion method. In this case, it is possible to adoptone of the following techniques as a technique of filling the interiorof the optical path between the projection optical system and thephotosensitive substrate with the liquid: the technique of locallyfilling the optical path with the liquid as disclosed in InternationalPublication WO99/49504; the technique of moving a stage holding thesubstrate to be exposed, in a liquid bath as disclosed in JapanesePatent Application Laid-open No. 6-124873; the technique of forming aliquid bath of a predetermined depth on a stage and holding thesubstrate therein as disclosed in Japanese Patent Application Laid-openNo. 10-303114, and so on. The teachings in WO99/49504, Japanese PatentApplication Laid-open No. 6 124873, and Japanese Patent ApplicationLaid-open No. 10-303114 are incorporated herein by reference.

The aforementioned embodiment was the application of the presentinvention to the illumination optical apparatus to illuminate the maskin the exposure apparatus, but, without having to be limited to this,the present invention can also be applied to any commonly-usedillumination optical apparatus to illuminate an illumination targetsurface other than the mask.

Embodiments and modifications of the present invention can be utilizedas an illumination optical apparatus suitably applicable to an exposureapparatus for manufacturing such devices as semiconductor devices,imaging devices, liquid-crystal display devices, and thin-film magneticheads by lithography.

The invention is not limited to the fore going embodiments but variouschanges and modifications of its components may be made withoutdeparting from the scope of the present invention. Also, the componentsdisclosed in the embodiments may be assembled in any combination forembodying the present invention. F or example, some of the componentsmay be omitted from all components disclosed in the embodiments.Further, components in different embodiments may be appropriatelycombined.

What is claimed is:
 1. An optical unit comprising: a light splitter,arranged in an incident light path, to split an incident beam travelingin the incident light path, into a plurality of beams; a first spatiallight modulator which can be arranged in an optical path of a first beamout of the plurality of beams; a second spatial light modulator whichcan be arranged in an optical path of a second beam out of the pluralityof beams; and a light combiner, arranged in an exiting light path, tocombine a beam having passed via the first spatial light modulator, witha beam having passed via the second spatial light modulator, and todirect a resultant beam to the exiting light path, wherein at least onespatial light modulator out of the first spatial light modulator and thesecond spatial light modulator includes a plurality of optical elementsarranged two-dimensionally and controlled individually, and wherein theincident light path on the light splitter side and the exiting lightpath on the light combiner side extend in the same direction.